Optical rotating device, illumination system and projection device

ABSTRACT

An optical rotating device includes a substrate having a first surface and a second surface opposite to each other, a rotating shaft connected to the substrate, a driving element connected to the rotating shaft and driving it to rotate, a wavelength conversion layer disposed on the first surface to convert a first laser beam into a converted beam, and a polarizing element disposed on the second surface. The first laser beam and at least one second laser beam are respectively transmitted to the wavelength conversion layer and the polarizing element from opposite directions. The driving element drives the substrate, the wavelength conversion layer and the polarizing element to rotate along the rotating shaft as a rotation central axis. When the polarizing element is rotated, the polarizing element makes the second laser beam have different polarization states at different times. An illumination system and a projection device are also provided.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the priority benefit of China application serialno. 201910427733.6, filed on May 22, 2019. The entirety of theabove-mentioned patent application is hereby incorporated by referenceherein and made a part of this specification.

BACKGROUND Technical Field

The invention relates to an optical rotating device, an illuminationsystem and a projection device.

Description of Related Art

Projection device is a display device used for generating large-scaleimages, and has been continuously improved along with development andinnovation of science and technology. An imaging principle of theprojection device is to use a light valve to convert an illuminationbeam generated by an illumination system into an image beam, and thenproject the image beam to a projection target (for example, a screen ora wall surface) through a projection lens to form a projection image.

Besides that a laser projection device may use a laser light generatedfrom a laser light source to excite phosphor powder to emit a convertedlight, it may also directly use laser diodes as a projector illuminationlight source, which has an advantage of adjusting the number of lightsources according to a brightness requirement, so as to achieveprojector requirements of various brightnesses.

However, in a known illumination system framework, a polarizationpolarity of a laser beam from the laser light source will be spoiled byoptical elements inside the projection device, resulting in scatteringof a polarization direction and intensity of the laser light, andcausing a problem of uneven brightness of a displayed image. Therefore,if a three-dimensional (3D) image is displayed in a polarizedstereoscopic mode (a projection lens with a polarizer disposed outsidethe projection lens), the image projected from the projection lens withthe polarizer may have a phenomenon of uneven image color or unevenbrightness.

The information disclosed in this Background section is only forenhancement of understanding of the background of the describedtechnology and therefore it may contain information that does not formthe prior art that is already known to a person of ordinary skill in theart. Further, the information disclosed in the Background section doesnot mean that one or more problems to be resolved by one or moreembodiments of the invention was acknowledged by a person of ordinaryskill in the art.

SUMMARY

The invention is directed to an optical rotating device, an illuminationsystem and a projection device, and when the projection device is in apolarized stereoscopic mode, a color or brightness of a display image isuniform, and a user may observe a stereoscopic display image with betteruniformity.

Other objects and advantages of the invention may be further illustratedby the technical features broadly embodied and described as follows.

In order to achieve one or a portion of or all of the objects or otherobjects, an embodiment of the invention provides an optical rotatingdevice including a substrate, a rotating shaft, a driving element, awavelength conversion layer and a polarizing element. The substrate hasa first surface and a second surface opposite to each other. Therotating shaft is connected to the substrate. The driving element isconnected to the rotating shaft, and is configured to drive the rotatingshaft to rotate. The wavelength conversion layer is disposed on thefirst surface of the substrate, and is disposed on a transmission pathof a first laser beam to convert the first laser beam into a convertedbeam. The polarizing element is disposed on the second surface of thesubstrate, and is disposed on a transmission path of at least one secondlaser beam, wherein the first laser beam and the at least one secondlaser beam are respectively transmitted to the wavelength conversionlayer and the polarizing element from opposite directions, the drivingelement is configured to drive the substrate, the wavelength conversionlayer and the polarizing element to rotate along the rotating shaftserving as a rotation central axis, and when the polarizing element isrotated, the at least one second laser beam is incident on thepolarizing element, and the at least one second laser beam outputtedfrom the polarizing element has different polarization states atdifferent times.

In order to achieve one or a portion of or all of the objects or otherobjects, an embodiment of the invention provides an illumination systemconfigured to provide an illumination beam. The illumination systemincludes a first laser light source unit, a second laser light sourceunit and the aforementioned optical rotating device. The first laserlight source unit is configured to emit a first laser beam. The secondlaser light source unit is configured to emit at least one second laserbeam. The optical rotating device is disposed on transmission paths ofthe first laser beam and the at least one second laser beam. Theillumination beam includes a converted beam and the at least one secondlaser beam.

In order to achieve one or a portion of or all of the objects or otherobjects, an embodiment of the invention provides a projection deviceincluding the aforementioned illumination system, at least one lightvalve and a projection lens. The at least one light valve is disposed ona transmission path of the illumination beam to convert the illuminationbeam into an image beam. The projection lens is disposed on atransmission path of the image beam.

Based on the above description, the embodiments of the invention have atleast one of following advantages or effects. In the optical rotatingdevice or the illumination system or the projection device equipped withthe optical rotating device of the invention, the driving element isconfigured to drive the substrate, the wavelength conversion layer andthe polarizing element to rotate along the rotating shaft serving as therotation central axis. Therefore, the at least one second laser beamoutputted from the polarizing element has different polarization statesat different times. In this way, when the projection device is in apolarized stereoscopic mode (the projection lens with a polarizerdisposed outside the projection lens), the color or brightness of thedisplay image is even, so that the user may observe the stereoscopicdisplay image with better uniformity through polarized stereoscopicglasses.

Other objectives, features and advantages of the present invention willbe further understood from the further technological features disclosedby the embodiments of the present invention wherein there are shown anddescribed preferred embodiments of this invention, simply by way ofillustration of modes best suited to carry out the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included to provide a furtherunderstanding of the invention, and are incorporated in and constitute apart of this specification. The drawings illustrate embodiments of theinvention and, together with the description, serve to explain theprinciples of the invention.

FIG. 1 is a schematic diagram of a projection device according to afirst embodiment of the invention.

FIG. 2 is a structural schematic diagram of an optical rotating deviceof FIG. 1.

FIG. 3 is a schematic diagram of an operation mode according to thefirst embodiment of the invention.

FIG. 4 is a schematic diagram of a projection device according to asecond embodiment of the invention.

FIG. 5 is a schematic diagram of an operation mode according to thesecond embodiment of the invention.

FIG. 6 is a schematic diagram of a projection device according to athird embodiment of the invention.

FIG. 7 to FIG. 9 are structural schematic diagrams of an opticalrotating device of FIG. 6 in different embodiments.

FIG. 10A to FIG. 10C are partial enlarged views of a region X in FIG. 9in different embodiments.

FIG. 11 is a schematic diagram of a projection device according to afourth embodiment of the invention.

DESCRIPTION OF THE EMBODIMENTS

In the following detailed description of the preferred embodiments,reference is made to the accompanying drawings which form a part hereof,and in which are shown by way of illustration specific embodiments inwhich the invention may be practiced. In this regard, directionalterminology, such as “top,” “bottom,” “front,” “back,” etc., is usedwith reference to the orientation of the Figure(s) being described. Thecomponents of the present invention can be positioned in a number ofdifferent orientations. As such, the directional terminology is used forpurposes of illustration and is in no way limiting. On the other hand,the drawings are only schematic and the sizes of components may beexaggerated for clarity. It is to be understood that other embodimentsmay be utilized and structural changes may be made without departingfrom the scope of the present invention. Also, it is to be understoodthat the phraseology and terminology used herein are for the purpose ofdescription and should not be regarded as limiting. The use of“including,” “comprising,” or “having” and variations thereof herein ismeant to encompass the items listed thereafter and equivalents thereofas well as additional items. Unless limited otherwise, the terms“connected,” “coupled,” and “mounted” and variations thereof herein areused broadly and encompass direct and indirect connections, couplings,and mountings. Similarly, the terms “facing,” “faces” and variationsthereof herein are used broadly and encompass direct and indirectfacing, and “adjacent to” and variations thereof herein are used broadlyand encompass directly and indirectly “adjacent to”. Therefore, thedescription of “A” component facing “B” component herein may contain thesituations that “A” component directly faces “B” component or one ormore additional components are between “A” component and “B” component.Also, the description of “A” component “adjacent to” “B” componentherein may contain the situations that “A” component is directly“adjacent to” “B” component or one or more additional components arebetween “A” component and “B” component. Accordingly, the drawings anddescriptions will be regarded as illustrative in nature and not asrestrictive.

FIG. 1 is a schematic diagram of a projection device according to afirst embodiment of the invention. FIG. 2 is a structural schematicdiagram of an optical rotating device of FIG. 1. Referring to FIG. 1,the projection device 200 of the embodiment is used for providing aprojection beam PB. The projection device 200 includes an illuminationsystem 100, at least one light valve 210 and a projection lens 220. Theillumination system 100 is used for providing an illumination beam IB.The at least one light valve 210 is disposed on a transmission path ofthe illumination beam IB to convert the illumination beam IB into animage beam IMB. The projection lens 220 is disposed on a transmissionpath of the image beam IMB, and is used for projecting the image beamIMB out of the projection device 200 to form the projection beam PB, andthe projection beam PB forms an image on a screen or a wall (not shown).Since after the illumination beam IB of different colors irradiates theat least one light valve 210, the at least one light valve 210 receivesthe illumination beam IB of different colors to output the image beamIMB in a time sequence, and transmits the image beam IMB to theprojection lens 220. Therefore, the image formed by the image beam IMBoutputted by the at least one light valve 210 and projected out from theprojection device 200 may be a color image. In the embodiment, thenumber of the light value 210 may be one, two or three, and operationmodes thereof are schematically described later with reference of FIG.3.

In the embodiment, the light valve 210 is, for example, a DigitalMicro-mirror Device (DMD) or a Liquid-Crystal-On-Silicon (LCOS) panel.However, in other embodiments, the light valve 210 may also be atransmissive liquid crystal panel or other spatial light modulator. Inthe embodiment, the projection lens 220 is, for example, one opticallens or a combination of a plurality of optical lens with refractivepower, and the optical lens, for example, includes a non-planar lenssuch as a biconcave lens, a biconvex lens, a concavo-convex lens, aconvexo-concave lens, a plano-convex lens, a plano-concave lens, etc, orvarious combinations thereof. The pattern and type of the projectionlens 220 are not limited by the invention.

Moreover, in some embodiments, the projection device 200 may selectivelyinclude optical elements with focusing, refracting or reflectingfunctions for guiding the illumination beam IB emitted by theillumination system 100 to the at least one light valve 210, and guidingthe image beam IMB outputted by the at least one light valve 210 to theprojection lens 220, so as to generate the projection beam PB, but theinvention is not limited thereto.

In application of the 3D display technique, the projection device 200 ofthe embodiment may be used as a polarized stereoscopic image projector.To be specific, when the two projection devices 200 are in apolarization stereoscopic mode (i.e., polarizers are disposed outsidethe projection lenses 220 or the polarizers are built in the projectiondevices 200), the projection beams PB provided by the two projectiondevices 200 may respectively pass through the polarizers to generateimages of different polarization states, a user may observe astereoscopic display image through polarized stereoscopic glasses, forexample, the polarized stereoscopic glasses worn by the user arerespectively equipped with two polarizing elements for a left-eye lensand a right-eye lens, and the two polarizing elements correspond to theimages with the polarization states generated by the polarizers of thetwo projection devices, such that the left and right eyes of the userrespectively receive the images projected by the correspondingprojection devices, so as to achieve the stereoscopic display effect.

As shown in FIG. 1, the illumination system 100 includes a first laserlight source unit 110, a second laser light source unit 120 and anoptical rotating device 130. The first laser light source unit 110 isconfigured to emit a first laser beam L1. The second laser light sourceunit 120 is configured to emit at least one second laser beam L2. In theembodiment, the second laser light source unit 120 includes a firstcolor laser light source 122 and a second color laser light source 124.The first color laser light source 122 and the second color laser lightsource 124 respectively emit a first color laser beam L22 and a secondcolor laser beam L24, where the at least one second laser beam L2includes the first color laser beam L22 and the second color laser beamL24.

In the embodiment, the first laser light source unit 110 and the firstcolor laser light source 122 and the second color laser light source 124of the second laser light source unit 120 are respectively laserlight-emitting elements including laser diodes. To be specific, thefirst laser light source unit 110 and the first color laser light source122 of the second laser light source unit 120 are, for example,respectively a blue laser diode bank, and the first laser beam L1 andthe first color laser beam L22 are respectively a blue laser beam. Thesecond color laser light source 124 of the second laser light sourceunit 120 is, for example, a red laser diode bank, and the second colorlaser beam L24 is a red laser beam. For example, a main wavelength (apeak wavelength) of the first laser beam L1 is, for example, 445 nm, amain wavelength of the first color laser beam L22 is, for example, 460nm, and a main wavelength of the second color laser beam L24 is, forexample, 638 nm, but the invention is not limited thereto. In theembodiment, the main wavelengths of the first laser beam L1 and thefirst color laser beam L22 are, for example, different, and in otherembodiments, the main wavelengths of the first laser beam L1 and thefirst color laser beam L22 may also be the same.

Referring to FIG. 1 and FIG. 2, in the embodiment, the optical rotatingdevice 130 may be a rotatable disk-like element, which is disposed ontransmission paths of the first laser beam L1 and the at least onesecond laser beam L2 (i.e. the first color laser beam L22 and the secondcolor laser beam L24). The optical rotating device 130 includes asubstrate SUB, a rotation shaft RA, a driving element 132, a wavelengthconversion layer 134 and a polarizing element 136. The substrate SUB hasa first surface S1 and a second surface S2 opposite to each other. Therotating shaft RA is connected to a center of the substrate SUB. Thedriving element 132 is connected to the rotating shaft RA, and isconfigured to drive the rotating shaft RA to rotate, so as to drive thesubstrate SUB to rotate along the rotation shaft RA serving as arotation central axis.

The wavelength conversion layer 134 is disposed on the first surface Siof the substrate SUB, and is disposed on the transmission path of thefirst laser beam L1 to convert the first laser beam L1 into theconverted beam CB, where main wavelengths of the first laser beam L1 andthe converted beam CB are different. The wavelength conversion layer 134is, for example, arranged on the first surface Si in an 0-ring shape,and cuts into the transmission path of the first laser beam L1 in arotating manner. The wavelength conversion layer 134 includes awavelength conversion substance, and the wavelength conversionsubstance, for example, includes a phosphor powder capable of generatinga yellow light beam and a phosphor powder capable of generating a greenlight beam (which are referred to as a yellow phosphor powder and agreen phosphor powder hereinafter). The yellow phosphor powder and thegreen phosphor powder are evenly blended and distributed in thewavelength conversion layer 134.

The polarizing element 136 is disposed on the second surface S2 of thesubstrate SUB, and is disposed on the transmission path of the at leastone second laser beam L2. The driving element 132 drives the substrateSUB, the wavelength conversion layer 134 and the polarizing element 136to rotate along the rotation shaft RA serving as the rotation centralaxis. When the polarizing element 136 is rotated, the at least onesecond laser beam L2 is incident on the polarizing element 136, and theat least one second laser beam L2 outputted from the polarizing element136 has different polarization states at different times. The polarizingelement 136 of FIG. 2, for example, entirely covers (attaches) thesecond surface S2 of the substrate SUB, however, in other embodiment,the polarizing element 136 may partially cover the second surface S2 ofthe substrate SUB, and a configuration range of the polarizing element136 may be determined according to an irradiation position of the secondlaser beam L2. For example, if the irradiation position of the secondlaser beam L2 is close to a peripheral area of the second surface S2 ofthe substrate SUB, the polarizing element 136 may be only disposed atthe peripheral area of the second surface S2 of the substrate SUB in aring shape. If the irradiation position of the second laser beam L2 isclose to a central area of the second surface S2 of the substrate SUB,the polarizing element 136 may be only disposed at the central area ofthe second surface S2 of the substrate SUB, so as to reduce unnecessarymaterial cost.

In the embodiment, the polarizing element 136 may be, for example, aquarter wave plate, a half wave plate, a depolarizer or a circularpolarizer. Since the second laser beam L2 is a polarized light (linearpolarization light), the second laser beam L2 irradiates differentpositions of the rotated polarizing element 136 at different times, andthe second laser beam L2 outputted from the polarizing element 136 maychange the polarization state in a time sequence due to the type of thepolarizing element 136. Therefore, when the polarizing element 136 isrotated, the second laser beam L2 outputted from the polarizing element136 may have different polarization states at different times. In otherwords, when the illumination system 100 operates, the second laser beamL2 with different polarization directions and light intensities may beoutputted rapidly and continuously through the rotation of opticalrotating device 130.

Due to a rotation speed of the optical rotating device 130, the secondlaser beam L2 of different polarization directions may be controlledwithin a range that cannot be perceived by human eye, the human eyeswill perceive an image with uniform intensity and no specificpolarization direction. For example, the rotation speed of the opticalrotating device 130 may be greater than or equal to 1800 revolutions perminute (rpm), which is, for example, 1800 rpm, 3600 rpm or 7200 rpm, butthe invention is not limited thereto. In this way, when the twoprojection devices 200 are in the polarization stereoscopic mode (i.e.,polarizers are disposed outside the projection lenses 220 or thepolarizers are built in the projection devices 200), the second laserbeams L2 outputted from the optical rotating devices 130 of the twoprojection devices 200 may further sequentially penetrate through theprojection lenses 220 and the polarizers to produce an image with evencolor and brightness on the screen, so that the user may observe thestereoscopic display image with better uniformity through the polarizedstereoscopic glasses.

It should be noted that the wavelength conversion layer 134 and thepolarizing element 136 are integrated into a same device. It isunnecessary to separately provide two independent rotating members. Thewavelength conversion layer 134 and the polarizing element 136 may sharethe same driving element 132, so that a mechanism design is simplifiedso as to improve flexibility of space application, reduce the cost andreduce a noise source.

In the embodiment, the first surface Si and the second surface S2 of thesubstrate SUB are reflective surfaces. Therefore, when the first laserbeam L1 is transmitted to the wavelength conversion layer 134, thewavelength conversion substance of the wavelength conversion layer 134is excited by the first laser beam L1 to emit the converted beam CB, andthe converted beam CB is reflected by the first surface S1 of thesubstrate SUB. When the second laser beam L2 is transmitted to thepolarizing element 136, the second laser beam L2 sequentially penetratesthrough the polarizing element 136, is reflected by the second surfaceS2 of the substrate SUB, and penetrates through the polarizing element136 again. In other words, the second laser beam L2 penetrates throughthe polarizing element 136 twice. In the embodiment, the first laserlight source unit 110 and the second laser light source unit 120 arerespectively located at two opposite sides of the optical rotatingdevice 130, and the wavelength conversion layer 134 and the polarizingelement 136 are respectively disposed on two opposite surfaces of thesubstrate SUB, where the first laser beam L1 and the second laser beamL2 are respectively transmitted to wavelength conversion layer 134 andthe polarizing element 136 from opposite directions, and the convertedbeam CB and the second laser beam L2 are respectively outputted inopposite directions.

In detail, the substrate SUB may be made of a metal material (forexample, aluminium), and the two opposite surfaces of the substrate SUBmay be coated with a coating layer (for example, silver) with highreflectivity, so as to reduce optical loss. Moreover, since the metalhas good thermal conductivity, the substrate SUB made of the metalmaterial avails heat dissipation of the wavelength conversion layer 134,so as to avoid reduction of optical conversion efficiency of thewavelength conversion layer 134 or burning the wavelength conversionlayer 134.

As shown in FIG. 1, the illumination system 100 further includes a lightcombining element 140, a light combining element 150, a lens 160, alight transmitting module 170, a light uniforming element 180 and adiffusion device 190. The light combining element 140 is disposed ontransmission paths of the first color laser beam L22 emitted from thefirst color laser light source 122 and the second color laser beam L24emitted from the second color laser light source 124, and locatedbetween the first color laser light source 122 of the second laser lightsource unit 120 and the optical rotating device 130. To be specific, thelight combining element 140 is, for example, a Dichroic Mirror (DM) or adichroic prism, and is adapted to provide different optical effects tolight beams of different colors. In the embodiment, the light combiningelement 140 is a Dichroic Mirror which reflects red light (DMR) thatallows the first color laser beam L22 (the blue laser beam) to passtherethrough and reflects the second color laser beam L24 (the red laserbeam), and the first color laser beam L22 and the second color laserbeam L24 coming from different transmission directions are guided to asame transmission direction after being outputted from the lightcombining element 140, so that the light combining element 140 may beused for transmitting the first color laser beam L22 and the secondcolor laser beam L24 coming from the second laser light source unit 120to the lens 160.

The lens 160 is disposed on the transmission paths of the first colorlaser beam L22 and the second color laser beam L24 (the second laserbeam L2) coming from the light combining element 140, and is locatedbetween the second laser light source unit 120 and the optical rotatingdevice 130. As shown in FIG. 1 and FIG. 2, the second laser beam L2emitted by the second laser light source unit 120 eccentricallypenetrates through the lens 160 and is incident to the polarizingelement 136, and the second laser beam L2 reflected by the secondsurface S2 of the substrate SUB eccentrically penetrates through thelens 160 and is transmitted to the light transmitting module 170. Inother words, when the second laser beam L2 emitted by the second laserlight source unit 120 is incident to the lens 160, a light spot formedby the second laser beam L2 on the lens 160 deviates from a central axis(an optical axis) of the lens 160, and when the second laser beam L2reflected by the second surface S2 of the substrate SUB is incident tothe lens 160, a light spot formed by the second laser beam L2 on thelens 160 also deviates from the central axis (the optical axis) of thelens 160. As shown in FIG. 1, the second laser beam L2 emitted by thesecond laser light source unit 120 is incident to a right half part ofthe lens 160, and the second laser beam L2 reflected by the substrateSUB is emitted out from a left half part of the lens 160.

The light transmitting module 170 includes a plurality of reflectionmirrors 172, the reflection mirrors 172 are disposed on the transmissionpath of the second laser beam L2, and are configured to transmit thesecond laser beam L2 coming from the polarizing element 136 to the lightcombining element 150.

The light combining element 150 is disposed on transmission paths of thefirst laser beam L1 coming from the first laser light source unit 110,the second laser beam L2 coming from the light transmitting module 170and the converted beam CB coming from the wavelength conversion layer134of the optical rotating device 130, and is located between the firstlaser light source unit 110 and the optical rotating device 130. To bespecific, the light combining element 150 is, for example, a dichroicmirror or a dichroic prism, and is adapted to provide different opticaleffects to light beams of different colors. In the embodiment, the lightcombining element 150 is a Dichroic Mirror which reflects yellow light(DMY) which allows the first laser beam L1 and the second laser beam L2to pass through and reflects the converted beam CB, so that the lightcombining element 150 is used for combining the second laser beam L2coming from the light transmitting module 170 and the converted beam CBcoming from the wavelength conversion layer 134, and transmitting thesame to the light uniforming element 180.

The light uniforming element 180 refers to an optical element capable ofuniforming a light beam passing through the light uniforming element180. In the embodiment, the light uniforming element 180 is disposed ontransmission paths of the second laser beam L2 and the converted beam CBcoming from the light combining element 150 to form the illuminationbeam IB for outputting to the at least one light valve 210. In otherwords, the illumination beam IB includes the second laser beam L2 andthe converted beam CB. In the embodiment, the light uniforming element180 is, for example, an integration rod. In other embodiments, the lightuniforming element 180 may also be a lens array or other optical elementhaving a light uniforming effect.

The diffusion device 190 is disposed on the transmission path of thesecond laser beam L2. The diffusion device 190 may be a rotatabledisk-like element, and the diffusion device 190 may be configured with adiffuser, diffusion particles or a diffusion structure for reducing oreliminating a speckle phenomenon of the second laser beam L2.

FIG. 3 is a schematic diagram of an operation mode according to thefirst embodiment of the invention. A process that the projection device200 provides the projection image is described below with reference ofFIG. 1 to FIG. 3 under conditions that, for example, the number of thelight valves 210 is two (for example, two DMDs are adopted), forexample, the light valves 210 include a light valve 210A and a lightvalve 210B, and a light splitting module (not shown) is disposed betweenthe light uniforming element 180 and the light valves 210 torespectively transmit the light beams of different colors to the lightvalve 210A and the light valve 210B.

Referring to FIG. 1 to FIG. 3, in a first time interval TA1, the firstlaser light source unit 110 is turned on to emit the first laser beam L1(for example, blue light), the first color laser light source 122 of thesecond laser light source unit 120 is turned off, and the second colorlaser light source 124 of the second laser light source unit 120 isturned on to emit the second color laser beam L24 (for example, redlight). In the first time interval TA1, the wavelength conversion layer134 of the optical rotating device 130 converts the first laser beam L1into the converted beam CB (for example, yellow green light). In thefirst time interval TA1, the light valve 210A and the light valve 210Bare switched to a first state, a green light part of the converted beamCB is incident to the light valve 210A, the second color laser beam L24and a red light part in the converted beam CB are incident to the lightvalve 210B. The light valve 210A converts the green light part of theconverted beam CB into a green image beam IMB-G, and the light valve210B converts the second color laser beam L24 and the red light part ofthe converted beam CB into a red image beam IMB-R. The green image beamIMB-G and the red image beam IMB-R are projected to a projection target(for example, a screen or a wall) through the projection lens 220 toform a green and red color image.

Referring to FIG. 1 to FIG. 3, in a second time interval TA2, the firstlaser light source unit 110 is turned off, the first color laser lightsource 122 of the second laser light source unit 120 is turned on toemit the first color laser beam L22 (for example, blue light), and thesecond color laser light source 124 of the second laser light sourceunit 120 is turned off. In the second time interval TA2, the light valve210A is switched to an idle state, and the light valve 210B is switchedto a second state. The first color laser beam L22 is incident to thelight valve 210B, and the light valve 210B converts the first colorlaser beam L22 into a blue image beam IMB-B. The blue image beam IMB-Bis projected to the projection target (for example, a screen or a wall)through the projection lens 220 to form a blue color image.

As described above, the projection device 200 projects the green imagebeam IMB-G and the red image beam IMB-R in the first time interval TA1,and projects the blue image beam IMB-B in the second time interval TA2to the projection target (for example, a screen or a wall), and based onthe principle of visual persistence of human eyes, the produced green,red, and blue color images may constitute a required color projectionimage.

Moreover, when the number of the light valves 210 is three (for example,3 DMDs are adopted), after the light valves are turned on, it isunnecessary to turn off the first laser light source unit 110 and thesecond laser light source unit 120 in different time intervals, and thethree light valves 210 respectively convert the second color laser beamL24 and the red light part in and the converted beam CB, the green lightpart in the converted beam CB and the first color laser beam L22 intothe red image beam IMB-R, the green image beam IMB-G and the blue imagebeam IMB-B according to a time sequence. Moreover, in some embodiments,the second laser light source unit 120 may not include the second colorlaser light source 124, and the red image beam IMB-R is provided by thered light part in the converted beam CB.

It should be noted that a part of content of the aforementionedembodiment is also used in the following embodiment, and descriptions ofthe same technical content are omitted, a part of the content of theaforementioned embodiment may be referred for description of the samedevices, and detailed descriptions thereof are not repeated in thefollowing embodiment.

FIG. 4 is a schematic diagram of a projection device according to asecond embodiment of the invention. Referring to FIG. 4, the projectiondevice 200 a of the embodiment is similar to the projection device 200of FIG. 1, and a main difference there between in framework is that theillumination system 100 a of the projection device 200 of the embodimentfurther includes a filter device FW, and the number of the light valve210 is one.

In the embodiment, the filter device FW may be a rotatable disk-likeelement, for example, a filter wheel. The filter device FW is configuredto filter (reflect or adsorb) beams other than a light beam of aspecific wavelength range and allow the light beam of the specificwavelength range to pass therethrough, so as to improve color purity ofthe color light to form the illumination beam IB. Moreover, thewavelength conversion substance of the wavelength conversion layer 134of the optical rotating device 130, for example, includes a phosphorpowder capable of generating a yellow light beam and a phosphor powdercapable of generating a green light beam (which are referred to as ayellow phosphor powder and a green phosphor powder hereinafter). Theyellow phosphor powder and the green phosphor powder are respectivelydisposed at different regions of the wavelength conversion layer 134,and the yellow phosphor powder and the green phosphor powder form an0-ring shape and sequentially cut into the transmission path of thefirst laser beam L1.

FIG. 5 is a schematic diagram of an operation mode according to thesecond embodiment of the invention. A process that the projection device200 a provides the projection image is described below with reference ofFIG. 4 to FIG. 5 under a condition that the number of the light valve210 is one (for example, one DMD is adopted), for example, the lightvalve 210C. In the embodiment, the filter device FW may include aplurality of sub-filter regions. For example, the filter device FW ofthe embodiment may include a green filter region GR, a red filter regionRR, a transparent region TR and a diffusion region DR.

Referring to FIG. 4 to FIG. 5, in a first time interval TB1, the firstlaser light source unit 110 is turned on to emit the first laser beam L1(for example, blue light), the first color laser light source 122 andthe second color laser light source 124 of the second laser light sourceunit 120 are turned off. In the first time interval TB1, the regionconfigured with the green phosphor powder in the wavelength conversionlayer 134 of the optical rotating device 130 is cut into thetransmission path of the first laser beam L1 to convert the first laserbeam L1 into the green converted beam CB, and the green filter region GRof the filter device FW is cut into a transmission path of the greenconverted beam CB to allow the green converted beam CB to passtherethrough. In the first time interval TB1, the light valve 210C isswitched to the first state, the green converted beam CB is incident tothe light valve 210C, and the light valve 210C converts the greenconverted beam CB into the green image beam IMB-G. The green image beamIMB-G is projected to the projection target (for example, a screen or awall) to form a green color image.

Referring to FIG. 4 to FIG. 5, in a second time interval TB2, the firstlaser light source unit 110 is continuously turned on to emit the firstlaser beam L1 (for example, blue light), the first color laser lightsource 122 of the second laser light source unit 120 is turned off, andthe second color laser light source 124 of the second laser light sourceunit 120 is turned on to emit the second color laser beam L24 (forexample, red light). In the second time interval TB2, the regionconfigured with the yellow phosphor powder in the wavelength conversionlayer 134 of the optical rotating device 130 is cut into thetransmission path of the first laser beam L1 to convert the first laserbeam L1 into the yellow converted beam CB, and the red filter region RRof the filter device FW is cut into the transmission path of the yellowconverted beam CB and the second color laser beam L24 to allow a yellowlight part of the converted beam CB and the second color laser beam L24to pass therethrough. In the second time interval TB2, the light valve210C is switched to the second state, a red light part of the yellowconverted beam CB and the second color laser beam L24 are incident tothe light valve 210C, and the light valve 210C converts the red lightpart of the yellow converted beam CB and the second color laser beam L24into the red image beam IMB-R. The red image beam IMB-R is projected tothe projection target (for example, a screen or a wall) to form a redcolor image. Moreover, in some embodiments, the second laser lightsource unit 120 may not include the second color laser light source 124,and the red image beam IMB-R is provided by the red light part in theyellow converted beam CB.

Referring to FIG. 4 to FIG. 5, in a third time interval TB3, the firstlaser light source unit 110 is continuously turned on to emit the firstlaser beam L1 (for example, blue light), the first color laser lightsource 122 of the second laser light source unit 120 is turned off, andthe second color laser light source 124 of the second laser light sourceunit 120 is turned off. In the third time interval TB3, the regionconfigured with the yellow phosphor powder in the wavelength conversionlayer 134 of the optical rotating device 130 is cut into thetransmission path of the first laser beam L1 to convert the first laserbeam L1 into the yellow converted beam CB, and the transparent region TRof the filter device FW is cut into the transmission path of the yellowconverted beam CB to allow the yellow converted beam CB to passtherethrough. In the third time interval TB3, the light valve 210C isswitched to a third state, the yellow converted beam CB is incident tothe light valve 210C, and the light valve 210C converts the yellowconverted beam CB into a yellow image beam IMB-Y. The yellow image beamIMB-Y is projected to the projection target (for example, a screen or awall) to form a yellow color image.

Referring to FIG. 4 to FIG. 5, in a fourth time interval TB4, the firstlaser light source unit 110 is turned off, the first color laser lightsource 122 of the second laser light source unit 120 is turned on toemit the first color laser beam L22 (for example, blue light), and thesecond color laser light source 124 of the second laser light sourceunit 120 is turned off. In the fourth time interval TB4, the diffusionregion DR of the filter device FW is cut into the transmission path ofthe first color laser beam L22 to allow the first color laser beam L22to pass therethrough and reduce or eliminate the speckle phenomenon ofthe first color laser beam L22. In the fourth time interval TB4, thelight valve 210C is switched to a fourth state, the first color laserbeam L22 is incident to the light valve 210C, and the light valve 210Cconverts the first color laser beam L22 into the blue image beam IMB-B.The blue image beam IMB-B is projected to the projection target (forexample, a screen or a wall) to form a blue color image.

As described above, the projection device 200 a projects the green imagebeam IMB-G to the projection target (for example, a screen or a wall) inthe first time interval TB1, projects the red image beam IMB-R to theprojection target in the second time interval TB2, projects the yellowimage beam IMB-Y to the projection target in the third time intervalTB3, and projects the blue image beam IMB-B to the projection target inthe fourth time interval TB4, so as to provide the green image beamIMB-G, the red image beam IMB-R, the yellow image beam IMB-Y and theblue image beam IMB-B in a time sequence, and based on the principle ofvisual persistence of human eyes, the produced green, red, yellow andblue color images may constitute a required color projection image.

FIG. 6 is a schematic diagram of a projection device according to athird embodiment of the invention. FIG. 7 to FIG. 9 are structuralschematic diagrams of the optical rotating device of FIG. 6 in differentembodiments. FIG. 10A to FIG. 10C are partial enlarged views of a regionX in FIG. 9 in different embodiments. Referring to FIG. 6 to FIG. 10C,the projection device 200 b of the embodiment is similar to theprojection device 200 of FIG. 1, and a main difference there between inframework is that in the illumination system 100 b of the projectiondevice 200 b of the embodiment, the diffusion device is integrated tothe optical rotating device. In other words, the embodiment does nothave the diffusion device 190 of FIG. 1, but the optical rotating device130 a further includes a diffusion element 138. The diffusion element138 is disposed on the second surface S2 of the substrate SUB, and isoverlapped with the polarizing element 136.

As shown in FIG. 7, the polarizing element 136 is located between thediffusion element 138 and the second surface S2 of the substrate SUB. Asshown in FIG. 8, the diffusion element 138 is located between thepolarizing element 136 and the second surface S2 of the substrate SUB.As shown in FIG. 9, FIG. 10A and FIG. 10B, the diffusion element 138 isdiffusion microstructures DMS, and the diffusion microstructures DMS aredisposed on any surface of the polarizing element 136, where thediffusion microstructures DMS may be disposed on the surface of thepolarizing element 136 away from the substrate SUB (FIG. 10A), and thediffusion microstructures DMS may also be disposed on the surface of thepolarizing element 136 facing the substrate SUB (FIG. 10B). As shown inFIG. 9 and FIG. 10C, the diffusion element 138 is the diffusionmicrostructures DMS, and the diffusion microstructures DMS are disposedon the second surface S2 of the substrate SUB. The diffusionmicrostructures DMS may be in arc shapes or in other suitable regular orin irregular shapes.

It should be noted that in the embodiment, the wavelength conversionlayer 134, the polarizing element 136 and the diffusion element 138 areintegrated into one device without separately configuring threeindependent rotating members, and the wavelength conversion layer 134,the polarizing element 136 and the diffusion element 138 may be drivento be rotated by the same driving element 132, so that a mechanismdesign is simplified so as to improve flexibility of space application,reduce the cost and reduce a noise source.

FIG. 11 is a schematic diagram of a projection device according to afourth embodiment of the invention. Referring to FIG. 11, the projectiondevice 200 c of the embodiment is similar to the projection device 200 bof FIG. 6, and a main difference there between in framework is that theillumination system 100 c of the projection device 200 c of theembodiment further includes the filter device FW, and the number of thelight valve 210 is one. Related descriptions of the filter device FW andthe operation mode of the embodiment may refer to description of thesecond embodiment, and details thereof are not repeated.

In summary, the embodiments of the invention have at least one offollowing advantages or effects. In the optical rotating device or theillumination system or the projection device equipped with the opticalrotating device of the invention, the driving element is configured todrive the substrate, the wavelength conversion layer and the polarizingelement to rotate along the rotating shaft serving as the rotationcentral axis. Therefore, the at least one second laser beam outputtedfrom the polarizing element has different polarization states atdifferent times. In this way, when the projection device is in apolarized stereoscopic mode (the projection lens with a polarizerdisposed outside the projection lens), the color or brightness of thedisplay image is even, so that the user may observe the stereoscopicdisplay image with better uniformity through polarized stereoscopicglasses. Moreover, by integrating the wavelength conversion layer andthe polarizing element and/or the diffusion element into the samedevice, it is unnecessary to respectively configure a plurality ofindependent rotation members, and the wavelength conversion layer andthe polarizing element and/or the diffusion element may be driven to berotated by the same driving element, so that a mechanism design issimplified so as to improve flexibility of space application, reduce thecost and reduce a noise source.

The foregoing description of the preferred embodiments of the inventionhas been presented for purposes of illustration and description. It isnot intended to be exhaustive or to limit the invention to the preciseform or to exemplary embodiments disclosed. Accordingly, the foregoingdescription should be regarded as illustrative rather than restrictive.Obviously, many modifications and variations will be apparent topractitioners skilled in this art. The embodiments are chosen anddescribed in order to best explain the principles of the invention andits best mode practical application, thereby to enable persons skilledin the art to understand the invention for various embodiments and withvarious modifications as are suited to the particular use orimplementation contemplated. It is intended that the scope of theinvention be defined by the claims appended hereto and their equivalentsin which all terms are meant in their broadest reasonable sense unlessotherwise indicated. Therefore, the term “the invention”, “the presentinvention” or the like does not necessarily limit the claim scope to aspecific embodiment, and the reference to particularly preferredexemplary embodiments of the invention does not imply a limitation onthe invention, and no such limitation is to be inferred. The inventionis limited only by the spirit and scope of the appended claims. Theabstract of the disclosure is provided to comply with the rulesrequiring an abstract, which will allow a searcher to quickly ascertainthe subject matter of the technical disclosure of any patent issued fromthis disclosure. It is submitted with the understanding that it will notbe used to interpret or limit the scope or meaning of the claims. Anyadvantages and benefits described may not apply to all embodiments ofthe invention. It should be appreciated that variations may be made inthe embodiments described by persons skilled in the art withoutdeparting from the scope of the present invention as defined by thefollowing claims. Moreover, no element and component in the presentdisclosure is intended to be dedicated to the public regardless ofwhether the element or component is explicitly recited in the followingclaims.

What is claimed is:
 1. An optical rotating device, comprising: a substrate, having a first surface and a second surface opposite to each other; a rotating shaft, connected to the substrate; a driving element, connected to the rotating shaft, and configured to drive the rotating shaft to rotate; a wavelength conversion layer, disposed on the first surface of the substrate, and disposed on a transmission path of a first laser beam to convert the first laser beam into a converted beam; and a polarizing element, disposed on the second surface of the substrate, and disposed on a transmission path of at least one second laser beam, wherein the first laser beam and the at least one second laser beam are respectively transmitted to the wavelength conversion layer and the polarizing element from opposite directions, the driving element is configured to drive the substrate, the wavelength conversion layer and the polarizing element to rotate along the rotating shaft serving as a rotation central axis, and when the polarizing element is rotated, the at least one second laser beam is incident on the polarizing element, and the at least one second laser beam outputted from the polarizing element has different polarization states at different times.
 2. The optical rotating device as claimed in claim 1, wherein the first surface and the second surface of the substrate are reflective surfaces.
 3. The optical rotating device as claimed in claim 1, wherein when the at least one second laser beam is transmitted to the polarizing element, the at least one second laser beam sequentially penetrates through the polarizing element, is reflected by the second surface of the substrate and again penetrates through the polarizing element.
 4. The optical rotating device as claimed in claim 1, wherein the polarizing element is a quarter wave plate, a half wave plate, a depolarizer or a circular polarizer.
 5. The optical rotating device as claimed in claim 1, further comprising: a diffusion element, disposed on the second surface of the substrate, and overlapped with the polarizing element.
 6. The optical rotating device as claimed in claim 5, wherein the polarizing element is located between the diffusion element and the substrate.
 7. The optical rotating device as claimed in claim 5, wherein the diffusion element is located between the polarizing element and the substrate.
 8. The optical rotating device as claimed in claim 5, wherein the diffusion element is diffusion microstructures, wherein the diffusion microstructures are disposed on any surface of the polarizing element or the second surface of the substrate.
 9. An illumination system, configured to provide an illumination beam, and comprising: a first laser light source unit, configured to emit a first laser beam; a second laser light source unit, configured to emit at least one second laser beam; and an optical rotating device, disposed on transmission paths of the first laser beam and the at least one second laser beam, and comprising: a substrate, having a first surface and a second surface opposite to each other; a rotating shaft, connected to the substrate; a driving element, connected to the rotating shaft, and configured to drive the rotating shaft to rotate; a wavelength conversion layer, disposed on the first surface of the substrate, and disposed on the transmission path of the first laser beam to convert the first laser beam into a converted beam, wherein the illumination beam comprises the converted beam and the at least one second laser beam; and a polarizing element, disposed on the second surface of the substrate, and disposed on the transmission path of the at least one second laser beam, wherein the first laser beam and the at least one second laser beam are respectively transmitted to the wavelength conversion layer and the polarizing element from opposite directions, the driving element is configured to drive the substrate, the wavelength conversion layer and the polarizing element to rotate along the rotating shaft serving as a rotation central axis, and when the polarizing element is rotated, the at least one second laser beam is incident on the polarizing element, and the at least one second laser beam outputted from the polarizing element has different polarization states at different times.
 10. The illumination system as claimed in claim 9, wherein the first surface and the second surface of the substrate are reflective surfaces.
 11. The illumination system as claimed in claim 9, wherein when the at least one second laser beam is transmitted to the polarizing element, the at least one second laser beam sequentially penetrates through the polarizing element, is reflected by the second surface of the substrate and again penetrates through the polarizing element.
 12. The illumination system as claimed in claim 9, wherein the polarizing element is a quarter wave plate, a half wave plate, a depolarizer or a circular polarizer.
 13. The illumination system as claimed in claim 9, further comprising: a diffusion device, disposed on the transmission path of the at least one second laser beam.
 14. The illumination system as claimed in claim 9, wherein the optical rotating device further comprises: a diffusion element, disposed on the second surface of the substrate, and overlapped with the polarizing element.
 15. The illumination system as claimed in claim 14, wherein the polarizing element is located between the diffusion element and the substrate.
 16. The illumination system as claimed in claim 14, wherein the diffusion element is located between the polarizing element and the substrate.
 17. The illumination system as claimed in claim 14, wherein the diffusion element is diffusion microstructures, wherein the diffusion microstructures are located on any surface of the polarizing element or the second surface of the substrate.
 18. The illumination system as claimed in claim 9, further comprising: a light combining element, disposed on the transmission paths of the first laser beam, the at least one second laser beam and the converted beam; and a light transmitting module, configured to transmit the at least one second laser beam coming from the polarizing element to the light combining element, wherein the light combining element combines the at least one second laser beam coming from the light transmitting module and the converted beam coming from the wavelength conversion layer.
 19. The illumination system as claimed in claim 18, further comprising: a lens, disposed on the transmission path of the at least one second laser beam and located between the second laser light source unit and the optical rotating device, wherein the at least one second laser beam emitted by the second laser light source unit eccentrically penetrates through the lens and is incident to the polarizing element, and the at least one second laser beam reflected by the second surface of the substrate eccentrically penetrates through the lens and is transmitted to the light transmitting module.
 20. A projection device, comprising: an illumination system, configured to provide an illumination beam, and comprising: a first laser light source unit, configured to emit a first laser beam; a second laser light source unit, configured to emit at least one second laser beam; and an optical rotating device, disposed on transmission paths of the first laser beam and the at least one second laser beam, and comprising: a substrate, having a first surface and a second surface opposite to each other; a rotating shaft, connected to the substrate; a driving element, connected to the rotating shaft, and configured to drive the rotating shaft to rotate; a wavelength conversion layer, disposed on the first surface of the substrate, and disposed on the transmission path of the first laser beam to convert the first laser beam into a converted beam, wherein the illumination beam comprises the converted beam and the at least one second laser beam; and a polarizing element, disposed on the second surface of the substrate, and disposed on the transmission path of the at least one second laser beam, wherein the first laser beam and the at least one second laser beam are respectively transmitted to the wavelength conversion layer and the polarizing element from opposite directions, the driving element is configured to drive the substrate, the wavelength conversion layer and the polarizing element to rotate along the rotating shaft serving as a rotation central axis, and when the polarizing element is rotated, the at least one second laser beam is incident on the polarizing element, and the at least one second laser beam outputted from the polarizing element has different polarization states at different times; at least one light valve, disposed on a transmission path of the illumination beam to convert the illumination beam into an image beam; and a projection lens, disposed on a transmission path of the image beam. 